Washing apparatus and oily water separation device and filtration device best suited to washing apparatus

ABSTRACT

A washing apparatus includes a bubbling wash section for impinging bubbles in washing liquid to a material such as a machined work to be washed so as to remove solids such as sludges and oils adhered to the material to be washed, and a sludge removal and oily water separation section for removing sludges or the like mixed with the washing liquid at the bubbling wash section and for separating oily water in the washing liquid, the washing liquid passed through said sludge removal and oily water separation section being returned to the initial bubbling wash section for circulation. An activated carbon filtration section for connection with the bubbling wash section is optionally provided.

TECHNICAL FIELD

The present invention relates to a washing apparatus and an oily waterseparation device and a filtration device best suited to the washingapparatus, and particularly to a washing apparatus suitable to wash awork obtained by a machining process such as a cutting process, agrinding process and a press working, and to an oily water separationdevice and a filtration device best suited to such a washing apparatus.

BACKGROUND OF THE INVENTION

Since cutting chips and machining oils are deposited on a machined work,a process for removing the cutting chips and the machining oils throughwashing is inevitably performed after the work has been machined.

Conventionally, in such a washing process, fleon, ethane, etc. are usedas washing liquids.

Such washing liquids such as fleon and ethane are excellent in theircleaning efficiency but may cause environmental pollution, andtherefore, their use will inevitably be inhibited in the near future.

For this reason, various kinds of washing liquids have been proposed foruse in place of fleon and ethane and have been practically used.However, waste liquids of most of the proposed washing liquids may notbe thrown out as they are after the washing process, and a specialdealer must be retained for disposing the waste liquids as industrialwastes. Therefore, there has been a problem that considerable expensesmust be born and that public nuisance may be caused in some cases.

For this reason, there has been desired for a washing apparatus whichcan be adapted for washing a work without using fleon or ethane andwithout using other types of washing liquids which involve the problemin their disposal. In connection with such a washing apparatus, therehas been desired for an oily water separation device operable toefficiently separate oily water after the washing process, and there hasbeen desired for an activated carbon filtration device operable toprovide clean filtrate.

It is, accordingly, an object of the present invention to provide awashing apparatus which is operable to efficiently perform a washingprocess by using water, and which permits the washing liquid to be usedin a recycle manner without being discharged to the outside as wasteliquid, and which brings reduction of the washing costs, and which caninhibit environmental pollution and public nuisance attendant thereon.

It is another object of the present invention to provide a washingapparatus which may improve the washing efficiency by substantiallyentirely removing the sludges or oils deposited on materials to bewashed and to reliably separate the removed sludges and oils from eachother through both an impinging action of high-pressurized washingliquid and an impinging action of fine bubbles on the materials.

It is a further object of the present invention to provide a washingapparatus which may minimize residual sludges and oils in a bubblingsection after removal and separation by bubbles in the bubbling section.

It is a still further object of the present invention to provide awashing apparatus in which removal of sludges and separation of oilywater is performed in a two-stage manner so as to reliably and smoothlyperform removal of the sludges and separation of the oily water and inwhich the life of the washing apparatus is improved.

It is a still further object of the present invention to provide awashing apparatus in which a washing process is efficiently performed intwo vessels including a first bubbling vessel and a second bubblingvessel.

It is a still further object of the present invention to provide an oilywater separation device which is best suited to a washing apparatus.

It is a still further object of the present invention to provide an oilywater separation device in which the separation of oily water can beefficiently performed.

It is a still further object of the present invention to provide an oilywater separation device in which the separation of oily water can beperformed with excellent accuracy.

It is a still further object of the present invention to provide an oilywater separation device in which the separation capability of acoalescer is excellently maintained so as to permit efficient separationof oily water.

It is a still further object of the present invention to provide an oilywater separation device which is simple in construction.

It is a still further object of the present invention to provide an oilywater separation device in which washing water can be effectivelyutilized without disposal.

It is a still further object of the present invention to provide anactivated carbon filtration device which is optimal for use with awashing apparatus.

It is a still further object of the present invention to provide anactivated carbon filtration device which may obtain clean filtrateliquid including no fine particles of activated carbon mixed thereinwhen starting a filtration process.

It is a still further object of the present invention to provide anactivated carbon filtration device which may reliably prevent fineparticles of activated carbon from flowing out from the device by meansof a filter.

It is a still further object of the present invention to provide anactivated carbon filtration device which improves the degree of freedomin selection and design of a supporting member for a filter and which iseconomic to manufacture and efficient in use.

It is a still further object of the present invention to provide anactivated carbon filtration device in which a filter can be easily andreliably mounted and in which fine particles of activated carbon arereliably prevented from flowing out from the device.

DISCLOSURE OF THE INVENTION

According to the present invention, there is provided a washingapparatus comprising a bubbling wash section for impinging bubbles inwashing liquid to a material such as a machined work to be washed so asto remove solids such as sludges and oils adhered to the material to bewashed, and a sludge removal and oily water separation section forremoving sludges or the like mixed with the washing liquid at thebubbling wash section and for separating oily water in the washingliquid, the washing liquid passed through the sludge removal and oilywater separation section being returned to the initial bubbling washsection for circulation. Thus, with the present invention, since thesolids such as sludges and oils adhered to the machined work are removedby impinging the bubbles in the washing liquid, the removal can beefficiently performed by using water as the washing liquid.Additionally, since the washing liquid passed through the sludge removaland oily water separation section is returned to the initial bubblingwash section for circulation, the washing liquid is not discharged tothe outside as waste water but is recycled.

Additionally, with this washing apparatus, it is preferable that thebubbling wash section includes a washing vessel for accommodating thematerial to be washed, and an aeration device for injecting the washingliquid mixed with bubbles into the washing vessel through a bubbleinjecting nozzle, the aeration device including a pump for pumping thewashing liquid into the bubble injection nozzle, and an air suctionvalve connected to the pump on its suction side, whereby the airsupplied from the air suction valve is converted into fine bubblesthrough a high-pressure mixing operation at the pump and is injectedtogether with the washing liquid at high pressure from the bubbleinjection nozzle. With this construction, since the air supplied fromthe air suction valve is converted into the fine bubbles through thehigh-pressure mixing operation at the pump and is injected together withthe washing liquid at high pressure from the bubble injection nozzle,the sludges and oils adhered to the material to be washed receives boththe impinging action of the high-pressure washing liquid and theimpinging action of the fine bubbles, so that the sludges and oils aresubstantially completely removed from the material to be washed, and inaddition, the removed sludges and oils reliably rise upwardly as themicro bubbles rise.

Further, preferably, the bubbling wash section includes as the washingvessel a bubbling vessel for receiving the material to be washed and forperforming the bubbling wash operation, and a receptor vessel forreceiving the upper layer part of the washing liquid in the bubblingvessel. A liquid-surface absorbing device is disposed within thereceptor vessel for introducing the washing liquid received by thereceptor vessel in sequence, beginning with the upper layer part of thewashing liquid, into the sludge removal and oily water separationsection. With this construction, the upper layer part in the bubblingvessel including the sludges and oils risen together with the risingbubbles is delivered to the receptor vessel. Also in the receptorvessel, the washing liquid is delivered in sequence, beginning with theupper layer part, into the sludge removal and oily water separationsection via the liquid-surface absorbing device. Therefore, the washingliquid is delivered in sequence, beginning with the part thereofincluding sludges and oils in rich, to the sludge removal and oily waterseparation section.

Furthermore, the sludge removal and oily water separation sectionpreferably includes a first sludge removal and oily water separationsection which utilizes the filtration operation without pressurizing thewashing liquid for removing the sludges, etc. and which utilizes thespontaneous separation of the oily water by buoyancy, and a secondsludge removal and oily water separation section which performs theremoval of the sludges, etc. and which performs the separation of theoily water by forced filtration with the pressurized washing liquid.With this construction, the removal of the sludges and the separation ofthe oily water is roughly performed without pressuring the washingliquid in the first sludge removal and oily water separation section,and then the removal of the sludges and the separation of the oily wateris precisely performed with the pressurized washing liquid in the secondsludge removal and oily water separation section. With this two-stageconstruction, the filter in the second sludge removal and oily waterseparation section may be prevented from an excessive load which may becaused by clogging, etc.

In addition, preferably, the bubbling vessel of the bubbling washsection includes a first bubbling vessel and a second bubbling vesselwhich receives the over-flow washing liquid from the first bubblingvessel, and the receptor vessel is adapted to receive the over-flowwashing liquid from the second bubbling vessel. With the bubbling vesselthus including the first bubbling vessel and the second bubbling vessel,the washing operation can be performed in a two-stage manner such that,for example, the first bubbling vessel receiving clear returning wateris utilized for a finishing washing operation, while the second bubblingvessel arranged on the downstream side of the first bubbling vessel isutilized for a rough washing operation.

Further, according to the present invention, there is provided an oilywater separation device comprising a body having an inlet of oily waterto be separated, and an oil outlet and a water outlet disposed on anupper side and a lower side of the body for discharging oil componentsand water components after separation, respectively, and a hollowcoalescer having therein an oily water passage connected to the inlet ofthe oily water to be separated, and a separated oil and water passagedisposed between the coalescer and a wall part of the body and incommunication with the oil outlet and the water outlet, so that the oilywater which enters at the inlet of the oily water into the oily waterpassage of the coalescer is separated into oil components and watercomponents through a wall of the coalescer, and wherein a partition wallis provided in the separated oil and water passage for producing arising flow of the oil and water components separated by the coalescer.With this construction, since the rising flow is imparted to the oil andwater components separated by the coalescer, the separated fine oilparticles positively rise without depending on their buoyancy.

Preferably, the partition wall has a substantially cylindricalconfiguration surrounding the coalescer and has an upper end determinedat substantially the same height as an upper end of the coalescer. Withthis construction, the separated oil/water may be risen to the height ofthe upper end of the coalescer.

Further, according to the present invention, there is provided an oilywater separation device comprising a body having an inlet of oily waterto be separated, and an oil outlet and a water outlet disposed on anupper side and a lower side of the body for discharging oil componentsand water components after separation, respectively; a hollow coalescerhaving therein an oily water passage connected to the inlet of the oilywater to be separated; and a separated oil and water passage disposedbetween the coalescer and a wall part of the body and in communicationwith the oil outlet and the water outlet, so that the oily water whichenters at the inlet into the oily water passage of the coalescer isseparated into oil components and water components through a wall of thecoalescer, wherein a back-washing device is provided for introducingwashing liquid into the separated oil and water passage, and passing thewashing liquid thorough the coalescer in a direction opposite to thedirection for separation of the oily water, and thereafter dischargingthe washing liquid to the outside of the body via the oily waterpassage. With this construction, emulsion-like oils, etc. which maycause clogging of the coalescer can be removed from the coalescer by theback-washing process.

The back-washing device may preferably include a back-washing watersupply pipe connected to the water outlet of the body, and aback-washing water discharge pipe connected to the inlet of the oilywater, so that the back-washing can be performed by utilizing the wateroutlet and the inlet of the oily water which are originally provided onthe body.

Further, preferably, the back-washing water supply pipe is connected toan outlet side of a separate oily water separation tank via a pump, andthe back-washing water discharging pipe is connected to the inlet sideof the oily water separation tank, so that the back-washing process canbe performed with the back-washing water circulated while theback-washing water is purified by the separate oily water separationtank.

According to the present invention, there is provided a filtrationdevice having activated carbon as filtration material disposed within afiltration tubular body, comprising a filter disposed on a filtrateflow-out side within the tubular body and permitting the filtrate topass therethrough but preventing the filtration material from passingtherethrough, a support member abutting on the filter on the filtrateflow-out side thereof and supporting the filter within the tubular bodyalong an inner circumferential wall of the tubular body, and a filtergroove formed by the outer periphery of the support member and the innerperipheral surface of the tubular body, the filter groove being coveredby the outer periphery of the filter.

With the filter groove thus covered by the outer periphery of thefilter, no gap is produced between the inner peripheral surface of thetubular body and the filter. Thus, the filter groove, more specifically,the outer periphery of the support member and the inner peripheralsurface of the cylindrical body are covered by the outer periphery ofthe filter in such a manner that the filter extends like a vertical wallalong the inner peripheral surface of the tubular body, so that thecreation of gap between the inner peripheral surface of the tubular bodyand the filter can be prevented. Further, by virtue of the grooveconfiguration, the filter can be reliably spread such that the filter isclosely fitted on the inner peripheral surface of the tubular body.Further, the filter may not cause displacement when the activated carbonis charged, and the filter is reliably put in place through charging ofthe activated carbon into the groove portion. The configuration of thefilter groove portion may be of substantially V-shaped configurationwith the outer periphery of the support member being configurated as aninclined plate which is oriented toward the inner peripheral surface ofthe tubular body and which is Inclined in a flow-out direction of thefiltrate liquid so as to form substantially V-shaped groove between theinner peripheral wall of the cylindrical body and the outer periphery ofthe support member. Otherwise, the groove configuration may be ofU-shaped configuration or of rectangular configuration. The grooveconfiguration may be selectively determined, with due consideration ofthe facility of covering by the filter, etc.

This filtration device is intended to prevent the fine particles ofactivated carbon from flowing out of the device, and the device includesat least the activated carbon as the filtration material. However, thedevice may contain different kind of filtration materials.

Further, any kinds of filters may be used as far as they can prevent thefiltration material from flowing out but do not prevent the filtratefrom passing therethrough. Such filters may be those made of non-wovenfabric, glass wool, absorbent cotton, woven or knitted fabric of naturalor synthetic fibers, papers, etc.

In addition, preferably, the filtration device includes a protrusionprovided on the outer periphery of the support member and oriented in aflow-in direction of the filtrate, so that the filter groove is formedby the outer periphery of the protrusion and the inner peripheralsurface of the tubular body. With the provision of the protrusion, thestate where the filter is engaged by the protrusion can be attained, sothat the filter groove can be reliably covered by the filter. Further,if the protrusion is covered by a flexible filter, the filter may beprevented from displacement or breakage, so that the filter can beuniformly spread.

The filter groove or the outer periphery of the support member and theinner surface of the tubular body are required to be covered by theouter periphery of the filter. Thus, if the filter groove is not coveredby the filter, fine particles located within the filter groove wouldpossibly be moved to flow out together with the filtrate through a gapbetween the support member and the tubular body or through the supportmember.

In addition, not only the outer peripheral side of the holder member,the inner peripheral wall of the tubular body must be covered by thefilter since, with the filter extending as a vertical wall along theinner peripheral surface of the body, the filter can be closely fittedon the inner peripheral wall of the tubular body by the activated carbonto be charged.

Further, if a filter having a size slightly smaller than the filterspread like a vertical wall is laid on the latter, the filter of theupper layer side may force the filter of the lower layer side to bereliably closely fitted on the inner peripheral wall of the tubularbody. When the activated carbon is charged in this state, the filter ofthe lower layer side may be further reliably closely fitted on the innerperipheral surface of the tubular body.

Thus, by covering the entire filter groove by the filter, no gap iscreated between the inner peripheral surface of the tubular body and thefilter while preventing the filter from displacement when the activatedcarbon is charged.

The support member is in abutment on the filtrate flow-out side of thefilter as described above and serves to hold the filter in apredetermined position within the tubular body along the innerperipheral surface of the tubular body.

Therefore, if the filter itself is not rigid and is not durable to thepressure applied from the filtration material and the filtrate liquid,the support member must have a configuration analogous to theconfiguration of interior of the tubular body and must have a partpermitting passage of the filtrate liquid.

If the filter itself is rigid, the support member may be disposed alongthe inner peripheral surface of the body such that the filter is heldonly at its outer peripheral portion.

In addition, the support member may serve to prevent passage of the fineparticles at the outer side of the filter and to permit the passage ofthe filtrate only at the central side of the filter.

Further, preferably, the filter is made of non-woven fabric, the supportmember is in abutment on the non-woven fabric and has a smaller sizethan the configuration of the interior of the tubular body, and thesupport member includes a plate member for permitting the filtrate toflow therethrough and a plate support member for supporting the platemember at the central side of the tubular body. The plate support memberhas a protrusion formed on the outer periphery thereof and orientedtoward the filtrate flow-into direction, so that the filter groove isformed by the outer periphery of the protrusion and the inner peripheralsurface of the tubular body. Thus, by constituting the support member incombination of a plural number of members, the plate member can bereliably held, and it is possible to design with due consideration ofthe strength and the filtration efficiency.

Further, preferably, the filtration device includes a lid detachablefrom the tubular body, and an annular recess is formed on an innerperipheral portion of an upper end of the tubular body so as to receivea seal ring for sealing between the tubular body and the lid. The filterincludes a filter member having an outer diameter greater than the innerdiameter of the filtration tubular body. The outer diameter of theannular recess is determined substantially equal to the diameter of thefilter member, so that a peripheral portion of the filter member can bebrought into engagement with the annular recess when the seal ring isremoved.

The present invention will become more fully apparent from the claimsand the description as it proceeds in connection with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the overall washing apparatus according toa first embodiment of the present invention;

FIG. 2 is a vertical sectional view of a bubbling wash section and afirst sludge removal and oily water separation section of the washingapparatus shown in FIG. 1;

FIG. 3 is a sectional view of an automatic air suction valve shown inFIG. 2;

FIG. 4 is a side view of an impeller incorporated into a volute pumpshown in FIG. 2;

FIG. 5 is a piping diagram of a second sludge removal and oily waterseparation section shown in FIG. 1:

FIG. 6 is a vertical sectional view of a washing apparatus according toa second embodiment of the present invention;

FIG. 7 is a vertical sectional view of an oily water separation devicefor use in the washing apparatus;

FIG. 8 is a schematic view of the overall washing apparatusincorporating an oily water separation device according to anotherembodiment of the present invention;

FIG. 9 is a vertical sectional view of a bubbling washing section and afirst sludge removal and oily water separation section of the washingapparatus shown in FIG. 8;

FIG. 10 is a vertical sectional view of the oily water separationdevice;

FIG. 11 is a piping diagram of a second sludge removal and oily waterseparation section including the oily water separation device;

FIG. 12 is a view illustrating in detail the construction of an upperportion and a lower portion of a filtration apparatus according to anembodiment of the present invention;

FIG. 13 is a view showing the overall filtration device;

FIG. 14 is a view showing another embodiment of a filtration materialreceiving portion;

FIG. 15 is a view showing a further embodiment of the filtrationmaterial receiving portion;

FIG. 16 is a view of the construction of an upper portion of afiltration device of another embodiment;

FIGS. 17(a), FIG. 17(b) and FIG. 17(c) are views showing steps insequence of positioning a lower non-woven fabric on the bottom of atubular body of the filtration device shown in FIG. 16; and

FIG. 18 is a view showing the construction of a lower portion of theconventional filtration device.

BEST MODES OF EMBODYING THE INVENTION

A washing apparatus according to a first embodiment of the presentinvention will now be explained with reference to FIGS. 1 to 5. Theoverall construction of the washing apparatus is shown in FIG. 1, andthe washing apparatus comprises a bubbling wash section 1 for receivinga machined work and for performing a washing process through bubbling aswill be explained later; a first sludge removal and oily waterseparation section 2 for removing solids such as sludges contained inwashing liquid (water or hot water) utilized in the bubbling washsection 1 and for subsequently separating the oily water; a secondsludge removal and oily water separation section 3 for further removingsmaller sludges and for further precisely separating the oily water; andan activated carbon filtration section 4 for clarifying the washingliquid used in the bubbling wash section 1 by means of activated carbon.Here, the washing liquid passed through the second sludge removal andoily water separation section 3 is returned to the initial bubbling washsection 1, so that a circulation path of bubbling wash section 1--firstsludge removal and oily water separating section 2--second sludgeremoval and oily water separating section 3--bubbling wash section 1 isformed.

The bubbling wash section 1 and the first sludge removal and oily waterseparation section 2 are shown in detail in FIG. 2. Firstly, anexplanation will be made in connection with the bubbling wash section 1.The bubbling wash section 1 is constituted mainly of a washing vessel 5for receiving the work, and an aeration device 6 disposed below thewashing vessel 5. The washing vessel 5 includes a bubbling vessel 7 forreceiving the work to be washed and an over-flow liquid receiving vessel9 separated from the bubbling vessel 7 by means of a partition wall 8.

A bubble injection nozzle 10 is disposed at the bottom of the bubblingvessel 7 and is connected to the aeration device 6. The aeration device6 forms a mixed flow of the washing liquid and fine bubbles as will beexplained later and the mixed flow is injected from the bubble injectionnozzle 10 so as to be impinged on the work, so that the sludges, oils,etc. adhered to the work surface rise together with the bubbles, toreach the upper layer part in the bubbling vessel 7. Here, by means ofthe above described circulation path, the washing liquid returned fromthe second sludge removal and oily water separation section 3 iscontinuously supplied to the bubbling vessel 7, so that the sludges,oils, etc. risen together with the bubbles to the upper layer part ofthe bubbling vessel 7 are flown over the partition wall 8 into theover-flow liquid receiving vessel 9 together with the washing liquid.

A liquid-surface absorbing device 11 is disposed within the over-flowliquid receiving vessel 9 and includes a vertical flow channel 11aformed therein and having an open upper end. A pipeline 12 is connectedto the lower portion of the liquid-surface absorbing device 11 andextends through a wall of the over-flow liquid receiving vessel 9 intothe first sludge removal and oily water separation section 2, so thatthe washing liquid flowing downwardly in the channel 11a is supplied tothe first sludge removal and oily water separation section 2 via thepipeline 12. Here, the liquid-surface absorbing device 11 is constructedsuch that the position of the upper end of the channel 11a is variablein a vertical direction and is known as a brand name "UP-DOWN SKIMMER".

The aeration device 6 will now be explained. The aeration device 6includes a volute pump 14 which has a suction side connected to thebottom of the over-flow liquid receiving vessel 9 via a pipeline 13A andwhich has a discharge side connected to the bubble injection nozzle 10via a pipeline 13B, and an automatic air suction valve 15 located on apart of the pipeline 13A adjacent the volute pump 14 or at a positionadjacent the volute pump 14 on the upstream side thereof. The volutepump 14 as well as its drive motor 16 is fixed to the lower portion ofthe bubbling wash section 1 and serves to pump the relatively cleanwashing liquid existing on the bottom side of the over-flow liquidreceiving vessel 9 and to atomize the air supplied from the automaticair suction valve 15 so as to deliver the atomized air to the bubbleinjection nozzle 10 together with the washing liquid.

The automatic air suction valve 15 is constructed such that the mixingratio of the air is automatically stably maintained irrespective of thedischarge amount from the volute pump 14, and the valve 15 incorporatesthe same construction as disclosed in Japanese Utility Model PublicationNo. 57-47439 in the name of the same applicant as the presentapplication. More specifically, as shown in FIG. 3, the automatic airsuction valve 15 includes a liquid-pressure introducing inlet 17 whichis connected to the discharge side of the volute pump 14 for introducinga part of the discharged washing liquid into a valve body 16; an airinlet 19 for introducing the air from the outside via an adjustablevalve mechanism 18; and an air outlet 21 in communication with the airinlet 19 via a piston valve 20. The air outlet 21 is connected to thepipeline 13A of the suction side. The piston valve 20 is normally biasedby a spring 22 in a direction to interrupt communication between the airinlet 19 and the air outlet 21, and a pressure receiving surface 23 isformed on the piston valve 20 for receiving the liquid pressure which isintroduced from the liquid-pressure introducing inlet 17. With thisconstruction, the piston valve 20 is lifted against the spring 22 inresponse to the liquid pressure applied to the pressure receivingsurface 23, so that the communication area between the air inlet 19 andthe air outlet 21 is increased and that the amount of air to beintroduced into the pipeline 13A is increased.

The air introduced into the pipeline 13A from the automatic air suctionvalve 15 is introduced into the volute pump 14 together with the washingliquid within the pipeline 13A, and the air is atomized by the volutepump 14 and is delivered to the bubble injection nozzle 10 together withthe washing liquid as described above. In this volute pump 14, animpeller 24 shown in FIG. 4 is incorporated. The impeller 24 has thesame construction as the impeller disclosed in Japanese PatentApplication No. 1-269588 (Japanese Laid-Open Patent Publication No.3-130598) in the name of the same applicant as the present application.More specifically, the impeller 24 has a basic construction in which aplurality of vanes 27 are formed on one side of a main plate 26 having acentrally positioned boss 25. The vanes 27 extend in an axial directionof the boss 25 and are equally spaced from each other in acircumferential direction. Fluid channels 28 are formed between each ofthe vanes 27, and each fluid channel 28 has a width gradually decreasingin a direction toward the outer periphery of the main plate 26,beginning from the position around the boss 25. Each of the vanes 27 hasa uniform thickness in the circumferential direction except a partadjacent the boss 25. The thickness of the part of each vane 27 adjacentthe boss 25 decreases in a direction toward the boss 25. Thus, sinceeach of the fluid channels formed between each of the vanes 27 has thewidth gradually decreasing toward the outer periphery of the main plate26, the impeller 24 may have an improved weight balance, and the headand the efficiency of the volute pump 24 are improved. These advantagesare further enhanced by the special determination of the thickness ofeach vane 27 as described above since the washing liquid may smoothlyflow into the area between each of the vanes 27.

As described above, with this embodiment, by virtue of combination ofthe automatic air suction valve 15 which is operable to automaticallystably maintain the air mixing ratio and the volute pump 14 which isexcellent in the head and the efficiency, the air is mixed within thevolute chamber at high pressure (3-5 Kg/cm²) so as to be atomized (a fewmicron, about 0.2 or 0.3 mm) and is injected from the bubble injectionnozzle 10 at high pressure while the atomized condition is stablymaintained.

The air thus atomized and injected at high pressure provides asubstantial effect for removing the sludges and oils when impinged onthe work, and can effectively convey the removed sludges and oils whenthey are raised by their buoyancy. The upper layer part of the washingliquid including the sludges and oils raised by the bubbles flow intothe over-flow liquid receiving vessel 9 over the partition wall 8, andthe upper layer part in the over-flow liquid receiving vessel 9including the sludges and oils in quantity is also introduced from theliquid-surface absorbing device 11 to the first sludge removal and oilywater separation section 2 via the pipeline 12.

The construction of the first sludge removal and oily water separatingsection 2 will now be explained with reference to FIG. 2. The firstsludge removal and oily water separation section 2 includes a sludgeremoving device 29 for removing solids such as sludges from the washingwater supplied from the bubbling wash section 1 via the pipeline 12, andthe first sludge removal and oily water separation section 2 alsoincludes an oily water separation tank 30 for separating the oily waterin the washing liquid which has been passed through the sludge removingdevice 29. The sludge removing device 29 is mounted on an upper portinof the oily water separation tank 30 and has a container-likeconfiguration for receiving the washing liquid which spontaneously flowsdown from the pipeline 12. The sludge removing device 29 has aconstruction in which a filter 32 made of layered non-woven fabric matsis put on an intermediate bottom-like perforated plate 31. The filter 32is formed by two or three pieces of mats which are laid one afteranother in such a manner that the mat having finer mesh is positioned insequence below one having a coarser mesh, so that the sludges having adiameter larger than about 10 microns can be removed. The washing liquidfrom which the sludges have been removed, spontaneously flows down intothe oily water separation tank 30 via a discharge pipe 33 connected tothe bottom of the sludge removing device 29.

The oily water separation tank 30 is divided into four sections or firstto fourth vessels 37A to 37D by two downwardly oriented partititionplates 36A and an upwardly oriented partition plate 36B positionedbetween the partition plates 36A. The partition plates 36A are mountedon a lid plate 34 and extend downwardly therefrom. The partition plates36A have lower ends spaced from a bottom plate 35 by suitable gaps. Thepartition plate 36B extends upwardly from the bottom plate 35 and formsa suitable gap between the partition plate 36B and the lid plate 34. Aslant plate 38 is mounted on an upper portion of the first vessel 37Afor receiving the washing liquid flowing douwnwardly from the dischargepipe 33. Therefore, the washing liquid is spontaneously separeted whenit flows downwardly along the slant plate 38, and the oils and water inthe washing liquid are separately positioned on the upper layer side andthe lower layer side in the first vessel 37A, respectively. The washingliquid positioned on the lower layer side underflows into the secondvessel 37B through the gap between the downwardly oriented partitionplate 36A positioned on the front side and the bottom plate 35, and thewashing liquid then flows into the third vessel 37C over the upwardlyoriented partition plate 36B. The washing liquid flown into the thirdvessel 37C subsequently underflows into the fourth vessel 37D throughthe gap between the downwardly oriented partition plate 36A positionedon the rear side and the bottom plate 35. By virtue of such repeatedunderflow and overflow, the separation of the oily water isaccellerated.

Further, an oil extraction cock 39 for discharging the separated oil tothe outside is disposed on a lateral side of the oily water separationtank 30 in a position at a suitable height above the upwardly orientedpartition plate 36B (communication area between the second vesssel 37Band the third vesssel 37C). In addition, an oil pot window 40 isdisposed on a front side of the oily water separation tank 30. With thisconstruction, an operator can operate the oil extraction cock 39 todischarge the risen and accumulated oil while visually recognizing theaccumulation state of the oil through the oil pot window 40. Other thanthe manual operation, the extration of the oil can be automaticallyperformed, for example, by actuating an open-close solenoid valve bymeans of an oil boundary surface sensor.

A liquid-surface abrsorbing device 41 similar to the liquid-surfaceabsorbing device 11 described in connection with the bubbling washsection 1 is disposed within the fourth vessel 37D, and a verticalchannel 11a of the liquid-surface absorbing device 41 has an open upperend and is connected to a pipeline 42 which extends through a wall ofthe oily water separation tank 30 into the second sludge removal andoily water separation section 3. Therefore, relatively clear washingliquid flown into the liquid-surface absorbing device 41 from the upperlayer part in the fourth vessel 37D is introduced into the second sludgeremoval and oily water separation section 3.

The second sludge removal and oily water separation section 3 serves toremove more fine sludges and to further precisely separate the oilywater while the washing liquid is forcibly passed through this section3. As shown in FIG. 1, the second sludge removal and oily waterseparation section 3 is constituted mainly of a filtration tube and anoily water separation tube. A piping system of this second sludgeremoval and oily water separation section 3 is shown in FIG. 3. Thepipeline 42 of the liquid-surface absorbing device 41 is connected tothe filtration tube 43 via a pump P, and the filtration tube 43 isconnected to the oily water separation tube 44 via a pipeline 45. Apressure-adjusting valve 46 is provided in the midway of the pipeline45. When the pressure of the washing liquid supplied to the oily waterseparation tube 44 exceeds a predetermined pressure, thepressure-adjusting valve 46 is operated to return a part of the washingliquid to the upstream side of the pump P or to the pipeline 42 via abypass pipeline 47.

Here, a filter of fine mesh (not shown) is disposed within thefiltration tube 43, and the washing liquid is forced and passed throughthe filter by the pump P, so that fine sludges (in the order of 3-1micron) are removed. The washing liquid is then delivered to the oilywater separation tube 44 via the pipeline 45. A fibrous tubular membercalled "coalescer" made of glass fiber, etc. is disposed within the oilywater separating tube 43. The washing liquid is forcibly passed frominside of the tubular member to the outside thereof in a radialdirection, so that the oil components and the water components areseparated to be accumulated in the upper layer and the lower layer atthe outside of the tubular member, respectively. The water components orthe washing liquid from which the oil components have been removed istaken out from the lower layer and is returned to the bubbling vessel 7of the bubbling section 1 via a pipeline 48. On the other hand, the oilcomponents are automatically discharged through actuation of a solenoidvalve 51 based on the detection of boundary surface by means of an oilboundary surface sensor 49 and a water boundary surface sensor 50 (seeFIG. 1). The oil boundary surface sensor 49 and the water boundarysurface sensor 50 are utilized for an open operation and a closeoperation, respectively, of the solenoid valve 51.

A typical construction of an oily water separation device utilized asthe oily water separation tube 44 is shown in FIG. 7. The oily waterseparation tube shown in FIG. 7 includes therein a tubular coalescer Amade of glass wool or other fibrous materials as an oily waterseparation layer. The washing liquid (emulsified oily water) isintroduced Into the interior of the coalescer A via the connectingpipeline 45 under pressure (0.2-1.0 Kg/cm²). The washing liquid isphysically separated into oil components and water components whilepassing through the coalescer A from inside thereof to the outside, andthe separated oil components are accumulated at the upper portion of theseparation device and are discharged to the outside through the solenoidvalve 51. On the other hand, the water components are discharged fromthe lower portion of the separation device to the pipeline 48.

Although the washing liquid (10-20 PPM in oil content) is returned tothe bubbling vessel 7 of the bubbling section 1 via the pipeline 49after the fine sludges have been removed and the oil components havebeen precisely removed as described above, in some cases, oil particlessuch as those having a diameter of about 0.05-0.03 mm flow out when theinner pressure of the coalescer is increased to about 1.5-2 Kg/cm² forexample. It appears that this phenomenon has been caused for the reasonthat, when the clogging has been caused to increase the inner pressureof the coalescer, the oil components absorbed onto the inner wall of thefibrous tubular body constituting the coalescer is pushed outwardlysince the inner wall is pushed by the inner pressure. The particles ofthe oil components which have been pushed outwardly are formed into aspherical configuration, and for example, when the washing liquid istaken out into a beaker and is put in a still standing state, theparticles of the oil rise to the surface to form a thin film on thesurface after 3-5 minutes have elapsed.

For this reason, with this embodiment, an oil absorption device 52 (seeFIG. 2) is disposed on an upper portion of the bubbling vessel 7, andthe washing liquid flown out from the pipeline 48 by opening thesolenoid valve 64 flows into the bubbling vessel 7 through the oilabsorption device 52. The oil absorption device 52 includes anabsorption mat 53 made of non-woven fabric of polypropylene family, andthe oil concentrate of 10-20 PPM can be obtained by using this mat 53,so that the separation accuracy can be stably maintained.

With the action of the coalescer of the oily water separation tube 44 ofthe second sludge removal and oily water separation section 3, forexample, when the operation of the second sludge removal and oily waterseparation section 3 is repeated after stopping the washing operation(after taking out the washed work), the oil concentration can be reducedto substantially 10 PPM by about 5 to 10 times of passing through thesecond sludge removal and oily water separation section 3 although itmay depend on the oil concentration in the washing liquid when thewashing operation has been stopped. Further, the incorporation of theoil absorption device 52 is advantageous in that the stability in theseparation accuracy can be obtained even if the coalescer is not in anormal operating condition, and that the life of the coalescer may beextended and that the costs may be substantially reduced.

As described above, with the circulation path of first bubbling washsection 1--first sludge removal and oily water separation section2--second sludge removal and oily water separation section 3--bubblingwash section 1, the removal of the sludges in the washing liquid and theseparation of the oily water therein can be highly accurately performed.However, particularly when the hot water washing has been performed, theclarity of the washing liquid may be degraded due to water scales orfine residual materials such as surface active agents, pigments and ironcomponents deposited on the work through evaporation of the water. Forthis reason, in this embodiment, the activated carbon filtration section4 is provided for clarifying the washing liquid in the bubbling washsection 1 by means of activated carbon as described previously. As shownin FIGS. 1 and 2, the activated carbon filtration section 4 is connectedto the bottom of the over-flow liquid receptor vessel 9 via a pipeline54, and the washing liquid in the over-flow liquid receptor vessel 9 ispumped by a pump (not shown) to forcibly pass the washing liquid throughan activated carbon layer (not shown), so that the water scales or thefine residual materials can be removed from the washing water, and thatthe washing water after filtration is returned to the bubbling vessel 7via a pipeline 55. Here, the activated carbon filtration section 4 isnot required to be always operated but may be operated occasionallyaccording to the degree of clarification of the washing liquid.

As described above, with this embodiment, firstly in the bubbling washsection 1, the sludges and oils adhered to the work to be washed areeffectively removed in the bubbling vessel 7 through impingement of thewashing liquid mixed with air on the work to be washed. Next, in thefirst sludge removal and oily water separation section 2, the sludgesare roughly removed while the oils are separated through naturalseparation and are removed. Subsequently in the second sludge removaland oily water separation section 3, the removal of sludges andseparation of the oily water is precisely performed, and the washingwater is then returned to the bubbling wash section 1. Thus, thisembodiment is advantageous in the following points: Firstly, theeffective washing can be performed by simply using water without usingwashing liquids such as fleon and ethane which involve the problem intheir disposal, and therefore, this embodiment is greatly useful forinhibiting the public pollution. In addition, since expensive wishingliquids as in the prior art are not required, the washing costs may bereduced. Further, the water after use in the washing operation is notdisposed but is again used in a circulation manner, so that theresources are nursed and that the washing costs are further reduced.

Particularly, in this embodiment, the aeration device 6 provides thewashing liquid including stably atomized air, and such washing liquid isinjected at high pressure from the bubble injection nozzle 10.Therefore, the sludges and oils adhered to the work are effectivelyremoved through both actions of the washing liquids and the fine bubblesinjected at high pressure, and they are risen as the bubbles rise to thesurface, so that an excellent washing effect can be obtained.

Additionally, the upper layer part of the washing liquids including thesludges and oils thus risen flows over the partition wall 8 into theoverflow liquid receiving vessel 9, and is introduced into the firstsludge removal and oily water separation section 2 via theliquid-surface absorbing device 11, beginning also with the upper layerpart of the washing liquids in the vessel 9 which include the sludgesand oils in quantity, so that the residual sludges or oils in thebubbling section 7 and the overflow liquid receiving vessel 9 can beminimized.

Further, prior to the forced sludge removing and oily water separationprocess by the pressure in the second sludge removal and oily waterseparation section 3, the sludge removing and oily water separationprocess is performed in the first sludge removal and oily waterseparation section 2 by gravity or spontaneous separation without usingpressure. Therefore, an excessive load which may be caused due toclogging of the filter adapted for removing the sludges or clogging ofthe coalescer adapted for separation of the oily water in the secondsludge removal and oily water separation section 3 can be reduced. Thismay provide advantages that the removal and separation process in thesecond sludge removal and oily water separation section 3 can besmoothly performed and that the life of the devices can be extended.

In addition, as described above, since the washing liquid is returnedfrom the second sludge removal and oily water separation section 3 tothe bubbling wash section 1 via the oil absorption device 52, it isadvantageous that an accidental flow of oils into the bubbling washsection 1 due to the abnormal functioning of the coalescer can beprevented, and that the safety in the separation accuracy can beobtained when the coalescer is in the normally functioning state.Further, the life of the coalescer can be extended to substantiallyreduce the costs.

The washing liquid can be maintained to be clean by occasionallyoperating the activated carbon filtration section 4 according to theclarification degree of the washing liquid.

A second embodiment of the present invention will now be explained withreference to FIG. 6. This embodiment is a modification to simplify theconstruction of the first embodiment. Like members are given the samereference numerals and their description will not be repeated.

This embodiment includes a bubbling wash section 1A, and a sludgeremoval and oily water separation section 2A which is the same as thefirst sludge removal and oily water separation section 2 of the firstembodiment where the washing liquid is not pressurized. The sludgeremoval and oily water separation section through forced separation isomitted in this embodiment.

A washing vessel 5A of the bubbling wash section 1A includes twobubbling vessels, a first bubbling vessel 7A and a second bubblingvessel 7B, and a first aeration device 6A and a second aeration device6B are disposed on the lower portions of their respective bubblingvessels. With this construction, the bubbling wash operation can beperformed in each of the first bubbling vessel 7A and the secondbubbling vessel 7B through the bubble injection nozzles 10 positioned attheir bottoms. The first bubbling vessel 7A and the second bubblingvessel 7B are separated by a partition wall 8A, so that the washingliquid flows over the partition wall 8A from the first bubbling vessel7A into the second bubbling vessel 7B. The overflow liquid receivingvessel 9 having the liquid-surface absorbing device 11 as provided inthe first embodiment is positioned adjacent the second bubbling vessel7B and is separated therefrom by means of a partition wall 8B, so thatthe washing liquid flows over the partition wall 8B from the secondbubbling vessel 7B into the overflow liquid receiving vessel 9.

As with the aeration device 6 of the first embodiment, each of the firstaeration device 6A and the second aeration device 6B includes the volutepump 14 and the automatic air suction device 15. The volute pump 14 ofthe first aeration device 6A has the suction side connected to thebottom of the first bubbling vessel 7A via a pipeline 56A and has thedischarge side connected to the bubble injection nozzle 10 disposedwithin the first bubbling vessel 7A via a pipeline 56B. Thus, the firstaeration device 6A performs the bubbling wash operation through acirculating flow within the first bubbling vessel 7A. On the other hand,the volute pump 14 of the second aeration device 6B has the suction sideconnected to the bottom of the overflow liquid receiving vessel 9 via apipeline 57A and has the discharge side connected to the bubbleinjection nozzle 10 disposed within the second bubbling vessel 7B via apipeline 57B. Thus, the second aeration device 6B serves to pump therelatively clean washing liquid existing on the bottom side of theoverflow liquid receiving vessel 9 so as to apply that washing liquidfor bubbling wash operation at the second bubbling vessel 7B.

The washing liquid flowing out of the liquid-surface absorbing device 11of the overflow liquid receiving vessel 9 via the pipeline 12 is adaptedfor removal of the sludges by the sludge removing device 29 and forseparation of the oily water by the oily water separation tank 30 in thesludge removal and oily water separation section 2A as in the firstsludge removal and oily water separation section 2 of the firstembodiment. The washing liquid is then flows to the outside from theliquid-surface absorbing device 41 via a pipeline 42A.

The pipeline 42A is connected to a returning pipeline 59 for returningthe washing liquid to the bubbling wash section 1A via a pump 58, sothat oils of the washing liquid flowing downwardly from the returningpipeline 59 is removed through absorption by the oil absorption device52 disposed above the first bubbling vessel 7A of the bubbling washsection 1A in the same manner as the first embodiment. The washingliquid is thereafter delivered to the first bubbling vessel 7A

As described above, the washing apparatus of the second embodiment is asimplified version of the apparatus of the first embodiment and does notinclude the sludge removal and oily water separation section withforcible separation. However, this apparatus is sufficient to cope witha work which is not so precisely required to remove sludges and toseparate oily water, and this apparatus can be constructed at lowercosts compared with the apparatus of the first embodiment.

Further, particularly in this embodiment, the washing vessel 5A of thebubbling wash section 1A includes two bubbling vessels, the firstbubbling vessel 7A and the second bubbling vessel 7B. In the firstbubbling vessel 7A, the bubbling wash operation is performed by usingthe clear washing liquid which is returned from the sludge removal andoily water separation section 2A via the oil absorption device 52. Onthe other hand, in the second bubbling vessel 7B, the bubbling washoperation is performed by using the relatively clear washing liquidexisting at the lower portion of the overflow liquid receiving vessel 9.Therefore, the washing operation of the work can be effectivelyperformed with the work replaced in sequence from the second bubblingvessel 7B to the first bubbling vessel 7A, such that the work to bewashed Is firstly entered to the second bubbling vessel 7B for roughwashing operation and that the work is then entered to the firstbubbling vessel 7A for finish washing operation. Thus, this embodimentis advantageous in that the total time required for the washingoperation is shortened compared with the case of the first embodimentwhich utilizes only one bubbling vessel 7.

Meanwhile, the coalescer A of the oily water separation tube 44 servesto separate the oily water through absorption of the oil on the fibrousmaterial constituting the coalescer A. Another embodiment of an oilywater separation device which utilizes the coalescer and which isimproved to further efficiently separate the oily water will now beexplained.

An oily water separation device 44A of this embodiment is adapted to beincorporated as one of the components of a washing apparatus as theabove described washing apparatus. The overall construction of thewashing apparatus incorporating the oily water separation device 44A isshown in FIG. 8 which corresponds to FIG. 1. A bubbling wash section anda first sludge removal and oily water separation section is shown inFIG. 9 which corresponds to FIG. 2. In these drawings, members that arethe same as those of the above embodiment are given like referencenumerals. As will be apparent from FIGS. 8 and 9, the change in thewhole washing apparatus is only the provision of a back-washing waterdischarge pipeline 161.

The construction of the oily water separation device 44A will now beexplained with reference to FIG. 10. The oily water separation device44A has a hollow cylindrical body 146. A hollow cylindrical coalescer147 made of fibrous material such as glass wool is disposed within thecylindrical body 146 and is positioned coaxially therewith. A pipeline145 from the filtration tube 43 is connected to an inlet 146A positionedat the lower portion of the body 146 for the oily water to be separated.The pipeline 145 is connected to a conduit 148 which is disposed withinthe lower portion of the body 146 and which has an upper part extendinginto the coalescer 147. Suitable number of radially oriented outletholes 149 are formed in the upper portion of the conduit 148 and areequally spaced from each other in the circumferential direction, so thatthe washing liquid from the pipeline 45 enters the interior of thecoalescer 147.

An upper end of the conduit 148 is threadably engaged with a lower endof a central shaft 150 of the coalescer 147. The central shaft 150 hasan upper portion which extends through the coalescer 147 and protrudesupwardly therefrom. A head 150a having a larger diameter is formed onthe upper end of the central shaft 150. A washer member 151 isinterposed between the head 150a and the upper end surface of thecoalescer 147. An annular flange 152 is mounted on the lower portion ofthe conduit 148 for supporting the lower portion of the coalescer 147,so that the coalescer 147 is held in position between the washer member151 and the flange 152.

A suitable gap is formed between the outer peripheral portion of theflange 152 and the inner wall of the body 146, and a cylindricalpartition wall 153 having an open upper end is mounted on the outerperipheral edge of the flange 152. The partition wall 153 is positionedcoaxially with the coalescer 147 and suitable gaps are formed betweenthe partition wall 153 and the outer wall of the coalescer 147 andbetween the partition wall 153 and the inner wall of the body 146,respectively. The height of the upper end of the partition wall 153 isdetermined to be substantially the same as the upper end of thecoalescer 147 or to be slightly higher than the latter. With thisconstruction, the washing liquid which is supplied from the pipeline 45via the pipeline to enter the interior of the coalescer 147 is separatedinto oil components and water components while passing through the wallof the coalescer 147 from the inside thereof to the outside and thenflows upwardly within the gap between the wall of the coalescer 147 andthe partition wall 153 as indicated by arrows in FIG. 10. As indicatedby the arrows of solid lines, the water components of the separatedwashing liquid flow over the upper end of the partition wall 153 andthen flows downwardly within the gap between the inner wall of the body146 and the partition wall 153 to reach the lower portion of the body146 where the water components enter the pipeline 48 connected to anoutlet 146B. The outlet 146B is disposed at the lower portion of thebody 146 for the separated water components. On the other hand, the oilcomponents are forced to be raised by the upwardly oriented flow withinthe gap between the wall of the coalescer 147 and the partition wall 153so as to be effectively separated and to be accumulated on the upperportion of the body 146.

A separated-oil discharge device 156 has a solenoid valve 155 and ismounted on an outlet 146C for the separated oil components. The outlet146C is positioned at the upper end of the body 146. Boundary surfacesensors 157 and 158 are mounted on the upper portion of a side surfaceof the body 146 and are spaced from each other in a vertical direction.When the amount of the separated oil components accumulated on the upperportion of the body 146 has been increased, a level Q of the boundarysurface between the oil components and the water components which havebeen separated from each other is lowered. Then the lower boundarysurface sensor 158 detects the level Q to open the solenoid valve 155,so that the separated oil components are automatically discharged by theseparated-oil discharge device 156. When the boundary surface level Q islifted and is detected by the upper boundary surface sensor 157, thesolenoid valve 155 is closed to automatically stop the discharge of theseparated oil components.

FIG. 11 corresponds to FIG. 5 of the previous embodiment and shows apipeline system of the second sludge removal and oily water separationsection 3 including the oily water separation device 44A. The pipeline42 extending from the liquid-surface absorbing device 41 of the oilywater separation device 30 is connected to the filtration tube 43 viathe pump through a pipeline 159, and the filtration tube 43 is connectedto the oily water separation device 44A via the pipeline 45. Aback-washing water supply pipeline 160 is adapted for introducing theback-washing water for the coalescer 147 of the oily water separationdevice 44A. The back-washing water supply pipe line 160 is connectedbetween a part on the side of the pump P of the pipeline 159, whichconnects the pump P to the filtration tube 43, and an outlet portion ofthe pipeline 48 for discharging the separated water component. Aback-washing water discharge pipeline 161 has one end connected to apart on the side of the oily water separation device 44A of the pipeline45 between the filtration tube 43 and the oily water separation device44A, and the back-washing water discharge pipeline 161 has the other endopened at the sludge removing device 29 of the oily water separationdevice 30.

A first open-close solenoid valve 162 is mounted on the pipeline 159,which connects the pump P to the filtration tube 43, at a position onthe downstream side of the connecting portion of the pipeline 159 to theback-washing water supply pipeline 160. A second open-close solenoidvalve 163 is mounted on the pipeline 45 which connects the filtrationtube 43 to the oily water separation device 44A. A third open-closesolenoid valve 164 is mounted on the pipeline 48, which is adapted fordischarging the separated water components, at a position on thedownstream side of the connecting portion of the pipeline 48 to theback-washing water supply pipeline 160. A fourth open-close solenoidvalve 165 is mounted on the midway of the back-washing water supplypipeline 160. A fifth open-close solenoid valve 166 is mounted on themidway of the back-washing water discharge pipeline 161. A back-washingsystem is constituted by the pump P, the back-washing water supplypipeline 160, the back-washing water discharge pipeline 161, the firstto fifth open-close solenoid valves 162 to 166 and the oily waterseparation tank 30. The first to fifth open-close solenoid valves 162 to166 are controlled to be opened and closed by a control device (notshown) in response to an oily water separation operation and aback-washing operation as follows:

    ______________________________________                                                  (oily water separation                                                                      (back-washing                                                   operation)    operation)                                            ______________________________________                                        First valve 162                                                                           open            close                                             Second valve 163                                                                          open            close                                             Third valve 164                                                                           open            close                                             Fourth valve 165                                                                          close           open                                              Fifth valve 166                                                                           close           open                                              ______________________________________                                    

Thus, during the back-washing operation, as indicated by the arrows ofdotted lines, the washing water delivered from the liquid-surfaceabsorbing device 41 of the oily water separation tank 30 enters theinterior of the body 146 through the pipeline 48 of the oily waterseparation device 44A for discharging the separated water via the pump Pand the back-washing water supply pipeline 160. The washing water isthen flows over the partition wall 153 into the space between thepartition wall 153 and the coalescer 147 and enters the interior of thecoalescer 147 while passing through the coalescer 147 from the outsidethereof to the inside in the opposite direction as the case of the oilywater separation operation. With this back-washing operation, theemulsion-like oils absorbed onto the fibrous layer of the coalescer 147are removed, and the washing water containing the emulsion-like oils isthen discharged from the pipeline 45 to the sludge removing device 29 ofthe oily water separation tank 30 via the back-washing water dischargepipeline 161. The washing water subsequently receives the separationaction at the oily water separation tank 30 in the same manner asdescribed above so as to be clarified and is thereafter delivered viathe back-washing water supply pipeline 160 to be used again for theback-washing operation.

By means of a timer provided in the previously described control device,the back-washing operation is automatically periodically performed for apredetermined time after the oily water separation operation has beenperformed for a predetermined time. For example, if a standard oilywater separation operation is performed at 15 liters/min and at 70° C.of the washing water temperature by using the coalescer 47 having adiameter of 150 mm and having a vertical height of 450 mm, theseparation ability can be renewed to the initial ability (the ability ofseparation at 15 liters/min) by performing the back-washing operation atintervals of 10 hours by using the back-washing water of 7 to 8 liters(30 seconds) to 9 to 10 liters (40 seconds). With this back-washingoperation, the life of the coalescer 147 can be extended by two to threetimes as that resulted when the operation has been continuouslyperformed without back-washing at 70° C. of the washing water.

The washing liquid which has received the separation action at the oilywater separation device 44A for precisely removing the oil contents isreturned to the bubbling vessel 7 of the bubbling section 1 via thepipeline 48. As described in the above embodiment, the oil absorptiondevice 52 is provided on the upper portion of the bubbling vessel 7, sothat the washing liquid flown out of the pipeline 48 flows downwardlyinto the bubbling vessel 7 via the oil absorption device 52. By virtueof the absorption mat 53 made of the non-woven fabric of polypropylenefamily of the oil absorption device 52, the oil contents are furtherremoved, so that the stability in the separation accuracy can beobtained.

In this embodiment, the removal of the sludges in the washing liquid andthe separation of the oily water therein can be highly accuratelyperformed by the circulation path of the bubbling wash section 1--thefirst sludge removal and oily water separation section 2--the secondsludge removal and oily water separation section 3--bubbling washsection 1. However, particularly when the hot water washing has beenperformed, due to water scales or fine residual materials such assurface active agents, pigments and iron components deposited on thework through evaporation of the water, the clarity of the washing liquidmay be degraded. In such a case, the washing liquid is passed throughthe activated carbon filtration section 4 in the same manner as thewashing apparatus of the first embodiment. Thus, the water scales or thefine residual materials are removed from the washing liquid whilepassing through the activated carbon layer in the activated carbonfiltration section 4, and the washing water thus filtered is thenreturned to the bubbling vessel 7 via the pipeline 70. Here, also inthis case, the activated carbon filtration section 4 is not required tobe always operated but may be operated occasionally according to theclarified degree of the washing liquid.

As described above, with the oily water separation device 44A of thisembodiment, the partition wall 153 is provided to coaxially surround thecoalescer 147 so as to create the upwardly oriented flow in the washingliquid after separation by the coalescer 147. Therefore, the separatedoil components are forced to be risen and the oil components areprevented from being mixed with the separated water components whichflow toward the pipeline 48, so that the separation operation can beefficiently performed.

An additional explanation will now be made for the operation forpreventing the oil contents from being mixed with the separated watercomponents. In case of the oily water separation device describedpreviously with reference to FIG. 7, the oil components separated whilepassing the separation layer A from the inside thereof to the outsideaccumulate at the upper portion of the separation tube depending only onits buoyancy. On the other hand, the separated water component isdischarged from the lower portion of the separation tube to the outsidevia the water outlet 48. Therefore, in some cases, the separated fineoil particles cannot rise enough but are mixed with the water so as tobe discharged from the water outlet 48 to the outside. Such mixing ofthe fine oil particles becomes frequent as the separation pressureincreases since the flow speed of the separated water component becomesgreater as the separation pressure increases. In contrast, with thisembodiment, the separated oil components are positively risen by theprovision of the partition wall 153, so that this embodiment serves toovercome the disadvantage of the oily water separation device of theprevious embodiment by preventing the separated oil particles from beingmixed with the water.

Additionally, since the height of the upper end of the partition wall153 is determined to be substantially the same height as the upper endof the coalescer 147 or to be slightly higher than the same, the risingaction of the oil components can be produced throughout the length ofthe coalescer 147, so that the separation accuracy can be furtherimproved.

Further, with this embodiment, since the back-washing system isconstituted by the pump P, the back-washing water supply pipeline 160,the back-washing water discharge pipe line 161, first to fifthopen-close solenoid valves 162 to 166 and the oily water separation tank30, the washing liquid is passed through the coalescer 147 in thedirection opposite to the separation direction, so that theemulsion-like oils absorbed onto the fibrous layer of the coalescer 147during a long-time separating operation can be removed. Therefore, theclogging of the fibrous layer of the coalescer 147 can be eliminated andthe separating operation of the oily water can be efficiently performed.

Thus, with the oily water separation device explained previously inconnection with FIG. 7, when the separating operation by means of theseparation layer A is performed for a long time, the inner pressure ofseparation layer A increases due to the resistance of the emulsion-likeoil components absorbed onto the fibrous layer. The absorbed oilcomponents may grow up to form oil drops of about 0.1 to 0.3 mm³ so asto form pores within the fibrous layers, and the oil drops consequentlyflow to the outside and are mixed with the separated water component.This may lower the separation accuracy and may degrade the separationefficiency, so that the coalescer A must be changed to new one. Incontrast, with this embodiment, the emulsion-like oil componentsabsorbed onto the fibrous layer can be removed by the back-washingoperation, so that the above drawbacks can be overcome.

Further, with the back-washing system of this embodiment, the washingwater delivered from the liquid-surface absorbing device 41 of the oilywater separation tank 30 is utilized as the washing water for theback-washing operation and is returned again to the oily waterseparation tank 30. Therefore, this system is economical since it doesnot require to newly introduce the washing water for the back-washingoperation. In addition, the back-washing operation can be performed byutilizing the pump P, the pipeline 45 for discharging the separatedwater, the outlet 146B, the pipeline 45 for supplying the oily water tobe separated, and the inlet 146A which are utilized for the separationoperation, so that this operation is advantages to simplify theconstruction. Further, with this embodiment, the back-washing operationis automatically periodically performed for a predetermined time bymeans of the timer of the control device after the oily water separationoperation has been performed for a predetermined time. Therefore, thisembodiment is advantageous in that the coalescer 147 can always maintainan excellent separation efficiency and that a longer life of thecoalescer 147 can be achieved by optimally determining the material andsize of the coalescer 147, the temperature of the washing water used forthe back-washing operation, the back-washing pressure, etc.

Although this embodiment incorporates both the construction in which thepartition wall 153 is provided and the construction in which theback-washing water supply pipeline 160, the back-washing water dischargepipeline 161 and the first to fifth open-close valves 162 to 165 areprovided for the back-washing operation, each of these constructionsindependently serves to improve the separation efficiency, andtherefore, only one of these constructions may be incorporated. However,it is a matter of course that the oily water separation efficiency canbe further improved by incorporating both these constructions as in thisembodiment.

Further, although this embodiment is optimally utilized for the washingapparatus of the embodiment shown in FIG. 1, it is a matter of coursethat this embodiment is not limited to use with the washing apparatusbut can be utilized as an independent oily water separation device.

A filtration device which can be optimally used as the activated carbonfiltration section 4 explained in connection with the washing apparatusof the first embodiment will now be explained with reference to FIGS. 12to 17.

The whole filtration device is shown by a sectional view in FIG. 13 andincludes activated carbon 202 as a filtration material. Liquids to betreated are supplied from the upside of the device and filtrate liquidsflow downwardly to the outside. The filtration device is constituted bya tubular body 204 filled with the activated carbon 202, a lid 206, abottom member 210, an activated carbon presser 216 and an activatedcarbon support 224.

Firstly, as shown in FIG. 12, the tubular body 204 is made of stainlesssteel and has a cylindrical configuration. The body 204 has an open topon which the lid 206 is fitted via an O-ring 205 as a packing member.

The lid 206 serves to close the open top of the body 204 and has acentral portion to which a pipe 208 is connected for charging theliquids to be treated into the tubular body 204 under pressure.

The tubular body 204 has an open bottom to which the bottom member 210is fixed by welding. The bottom member 210 serves to close the openbottom of the tubular body 204 and to support the activated carbon 202filled within the tubular body 204, the activated carbon presser 216 andthe activated carbon support 230.

A discharge pipe 12 is connected to the central portion of the bottommember 210 for discharging clarified liquids or the filtrate liquidswhich have been passed through the activated carbon 202.

The internal construction of the tubular body will now be explained withreference to FIGS. 12 and 13.

As shown in FIG. 13, the activated carbon 202 is uniformly filled withinthe tubular body 204 and forms a filtration layer F.

The activated carbon presser 216 is positioned above the filtrationlayer F. More specifically, in order to press the activated carbon 202,the activated carbon presser 216 is formed by a non-woven fabric 218 forabutting on the whole upper surface of the filtration layer F and aperforated plate 220 laid on the non-woven fabric 218 for preventing thenon-woven fabric 218 from floating. The perforated plate 220 has waterpassing holes 220a formed therethrough.

The non-woven fabric 218 is selected to have a density not to permitpassage of water to be treated.

In addition, the perforated plate 220 utilized in this embodiment has aweight sufficient to press the non-wove fabric 218 by its gravity.

Thus, in this embodiment, the non-woven fabric 218 is in a statecompressed by the gravity of the perforated plate 220. Therefore, whenthe liquids to be treated are introduced and passed through thenon-woven fabric 218, the resistance within the non-woven fabric 218 toprevent passage of the liquids increases, so that the liquids aredispersed over the whole non-woven fabric 218 and that the liquids mayuniformly pass through the filtration layer F in section.

Although in this embodiment, the non-woven fabric 218 is compressed bythe gravity of the perforated plate 220, the non-woven fabric 218 may becompressed by the perforated plate 220 with the perforated plate 220held by a suitable holder.

The activated carbon support 224 is disposed below the filtration layerF.

The activated carbon support 224 is constituted by a filter 246 and asupport 230 for supporting the filter 246. The filter 246 serves toprevent the activated carbon 202 from flowing out therethrough but notto prevent passage of the filtrate liquids.

The support 230 is formed by a plate 232 and a plate support member 234.The plate 232 has a number of water passing holes 232a formedtherethrough, and the plate support member 234 serves to hold the plate232 in a predetermined position within the tubular body.

The plate support member 234 has a substantially circular configurationand is laid on the bottom member 210. A hole 234a is formed through thecentral portion of the plate support member 234 for introducing thefiltrate water to the discharge pipe. A vertical wall 236 is formed onthe outer periphery of the plate support member 234 and extends alongthe inner peripheral surface of the tubular body.

The plate support member 234 has an upper surface (hereinafter called"filtrate liquid passing portion) 238 positioned inwardly of thevertical wall 236. A plurality of grooves V are formed on the filtrateliquid passing portion 238 along the radial direction thereof, so thatthe plate 232 is supported by apexes of the grooves V at theircorresponding positions and that the bottoms of the grooves V formpassages for the filtrate liquids. The filtrate liquids are thereforedischarged from the central hole 234a through the filtrate liquidpassing portion 238.

The vertical wall 236 of the plate support member 234 is formed like astepped portion extending upwardly along the outer peripheral edge ofthe filtrate liquid passing portion 238 and includes a protrusion part240 oriented upwardly of the tubular body 204 and toward the center ofthe tubular body 204. The protrusion part 240 has a ring-likeconfiguration and extends along the inner peripheral surface of thetubular body 4.

More specifically, the protrusion part 240 is formed on the verticalwall 235 on the side of the center of the tubular body and protrudesupwardly at an angle of about 45°, so that a substantially V-shapedfilter groove 242 is formed between the protrusion part 240 and theinner peripheral surface of the tubular body 204.

The plate 232 is placed on the upper side of the filtrate liquid passingportion 238 of the plate support 234 thus constructed.

The plate 232 having the water passing holes 232a is a circularperforated plate made of stainless steel and having a diameter smallerthan the inner diameter of the tubular body 204. The plate 232 is laidon the filtrate liquid passing portion 238 and is held in positionrelative to the tubular body with its outer periphery surrounded by thevertical wall 236.

Thus, the vertical wall 236 on the side of outer periphery of the plate232 forms a filtration stopper portion for stopping the passage of thefiltrate liquids.

In this embodiment, the filter 246 laid on the plate 232 includes twonon-woven fabrics or upper and lower non-woven fabrics 246a and 246b.

Further, in this embodiment, a non-woven fabric having a predetermineddensity is utilized as each of the non-woven fabrics 246a and 246b, andthe non-woven fabric 246b on the lower layer side has a circularconfiguration having a diameter larger than the inner diameter of thetubular body 204 by 5%, while the non-woven fabric 246a on the upperlayer side has a circular configuration having a diameter substantiallyequal to the inner diameter of the tubular body 204.

The filter 246 is adapted to also cover the inner peripheral surface ofthe tubular body 204 as well as the protrusion part 240 forming thefilter groove 242. In view of the displacement of the non-woven fabrics246a and 246b when the activated carbon is charged, and in view of theconfigurations of the protrusion part 240 and the filter groove 242, thesize of each of the non-woven fabrics 246a and 246b must be determinedand the construction of the filter 246 must be determined as to whetherit may have one-sheet construction.

As shown in FIG. 12, in this embodiment, the non-woven fabric 246b onthe lower layer side covers the upper surface of the plate 232 and alsocovers the filter groove 242 by its outer peripheral portion such thatthe outer peripheral portion extends like a vertical wall closely fittedon the inner peripheral surface of the tubular body.

In this connection, with this embodiment, the height of the non-wovenfabric 246b which acts as a vertical wall for covering the innerperipheral surface 204 of the tubular body 204 is substantially equal tothe height of the non-woven fabric 246a for covering the plate 232. Asthe result, the covering operation by the non-woven fabric 246a can beeasily made, and the non-woven fabrics 246a and 246b are compressed bythe charged activated carbon without causing the non-woven fabric 246bto be bent inwardly when the activated carbon has been charged.

The non-woven fabric 246a on the upper layer side is spread over thenon-woven fabric 246b on the lower layer side such that the non-wovenfabric 246a covers the plate 232 and the protrusion part 240 and that itabuts on the corner of the filter groove 242 which is covered by thenon-woven fabric 246b.

As the result, the filter groove 242 is covered by the non-woven fabric246b along the contour of the filter groove 242 and substantially halfthe filter groove 242 covered by the non-woven fabric 246b is furthercovered by the non-woven fabric 246a on the upper layer side, so thatthe filter 246 as a whole covers the filter groove 242 and is filledinto the same.

The non-woven fabrics 246a and 246b is positioned during the charging ofthe activated carbon such that two non-woven fabrics 246a and 246b arepressed by the activated carbon not to produce any gap therebetween andthat the non-woven fabrics 246a and 246b are pressed into the filtergroove 242 by the activated carbon 202.

The operation of the above filtration device will now be explained.

Firstly, when the liquids to be treated or the polluted liquids areintroduced into the filtration device, the polluted liquids reach theactivated carbon presser 216 at the upper portion of the tubular body204 via the pressure-charging pipe 208.

At the activated carbon presser 216, the polluted liquids are diffusedin a horizontal direction as well as in a downward direction within thenon-woven fabric 218 which has been pressed by the perforated plate 220and which has been compressed, so that the liquids uniformly diffuse theoverall section of the filtration layer F.

At the filtration layer F, the polluted liquids pass through theuniformly charged activated carbon 202, and due to the pressure of thepassing polluted liquids, fine particles of the activated carbon aregradually moved toward the lower portion of the tubular body 204.

Most of the fine particles are captured by the non-woven fabrics 246aand 246b which are placed on the plate 232 of the activated carbonsupport 224.

Further, the fine particles which may pass an area along the innerperipheral surface of the tubular body 204 are also captured by thenon-woven fabrics 246a and 246b which cover the filter groove 242 andextend to the inner peripheral surface of the tubular body 204.

Particularly with this embodiment, the non-woven fabric 246b at thefilter groove 242 completely reaches the inner peripheral surface of thetubular body 204 by the vertical wall, and the non-woven fabric 246a isspread over this place, so that the fine particles can be reliablycaptured.

As described above, with this embodiment, the filter groove 242 isdisposed along the inner peripheral surface of the tubular body 204, andthe filter groove 242 is covered by the non-woven fabrics 246a and 246b,so that the fine particles can be reliably prevented from flowing outthrough a gap which would not be created between the inner peripheralsurface of the tubular body 204 and the filter 246.

In contrast, as shown in FIG. 13, a conventional activated carbonfiltration device has a construction in which a non-woven fabric 310 asa filtration material stopper has a size substantially equal to theinternal section of a tubular body 300. The non-woven fabric 310 isdisposed within a lower portion of the tubular body 300 and is supportedby a perforated plate 320 and a filtration material support member 330.With this construction, a gap S may possibly be created between thenon-woven fabric 310 and the inner peripheral surface of the tubularbody 300. If such a gap has been created, filtrate liquids may flowthrough the gap between the filtration material support member 330 andthe inner peripheral surface of the tubular body 300 as well as throughwater passing holes formed in the perforated plate 320. Further, whenthe water is filtered for the first time after charging the filtrationmaterial or when the filtration process is again started after theprocess has been once stopped, the pressure may be abruptly applied tothe activated carbon within the tubular body. For this reason, fineparticles contained in the charged activated carbon may move along theinner peripheral surface of the tubular body 300. In this occasion, ifthe gap S has been created between the non-woven fabric 310 and thetubular body 300 as described above, the fine particles are moved toflow together with the filtrate liquids along the inner peripheralsurface of the tubular body 300 or through the perforated plate 320 viathe gap S, so that the fine particles of the activated carbon areinconveniently mixed with the filtrate liquids immediately afterstarting the filtration operation.

According to the above embodiment, these drawbacks of the conventionalactivated carbon filtration device can be completely overcome.

Although in the above embodiment, the filter grove 242 is covered by twosheets of overlaid non-woven fabrics, the present invention is notlimited to this construction.

Further, although in this embodiment, the filter groove 242 is formed asa groove between the protrusion part 240 of the vertical wall 236 at theouter periphery of the plate support 234 and the inner peripheralsurface of the tubular body, the present invention is not limited tothis construction.

For example, as shown in FIG. 14, a plate support 250 may have an outerperiphery which does not include a vertical wall but is merelydownwardly inclined toward the inner peripheral surface of a tubularbody 251, so that a filter groove 252 is formed between the inclinedportion and the inner peripheral surface of the tubular body 251.

Preferably in this case, a filter 253 which is spread to form a verticalwall along the inner peripheral surface of the tubular body 251 has aheight equal to or greater than the height of the plate, so that thefilter 253 is formed with a grooved configuration along the filtergroove 252. With such a grooved configuration, an additional filter canbe easily overlaid, and the filter 253 can be reliably closely fitted onthe inner peripheral surface of the tubular body 251 when the activatedcarbon has been charged.

Additionally, as shown in FIG. 15, the plate and the plate support maybe formed not to be separated from each other but is formed integrallyas a support member 270, and the outer periphery of the support member270 is inclined downwardly and toward the inner peripheral surface of atubular body 271 so as to form a filtration stopper portion, so that afilter groove 272 is formed between the outer periphery of the supportmember 270 and the inner peripheral surface of the tubular body and iscovered by the filter 273.

Of course, the filtration device of the above embodiment is not limitedto the use as one of components of the washing apparatus but may beindependently utilized.

Further, although the non-woven fabrics 246a and 246b are pressed intothe filter groove 242 by the gravity of the activated carbon 202 asdescribed above, it is preferable that the non-woven fabrics 246a and246b are accurately positioned relative to the filter groove 242 at thebottom of the tubular body 204 prior to the pressing operation by theactivated carbon 202 or prior to charging the activated carbon 202. Anembodiment optimum for such positioning will now be explained withreference to FIG. 16, and FIGS. 17(a) to 17(c). The construction otherthan that shown in these drawings are the same as the embodiment shownin FIGS. 12 and 13.

In the embodiment shown in FIG. 16, similar to the embodiment shown inFIG. 12, between a flange portion 352 formed on the outer periphery ofthe upper end of the tubular body 204 and a flange portion 352 of a lid356 confronting the flange portion 352, an O-ring 353 is interposed forsealing therebetween. An annular recess 354 for receiving the O-ring 353is formed in the inner periphery of the upper surface of the flangeportion 351 positioned at the upper end of the tubular body 204. The lid156 is detachable from the tubular body 204 by means of bolts 356a.Here, the height of an upper edge 204a of the tubular body 204 isdetermined to be substantially the same as the height of the bottomsurface of the annular recess 354, and the diameter of the outerperiphery of the annular recess 354 is determined to be substantiallythe same as the diameter of the non-woven fabric 246b which is the lowerlayer side of the lower non-woven fabrics 246a and 246b, so that thediameter of the outer periphery of the annular recess 354 is greaterthan the inner diameter of the tubular body 204 by 5%. The diameter ofthe non-woven fabric 246a on the upper layer side is determined to besubstantially equal to, the inner diameter of the tubular body 204 asdescribe previously.

FIG. 16 shows the state where the activated carbon 202 has been chargedand where the upper non-woven fabric 218 has been placed on theactivated carbon 202. A non-woven fabric compressing plate 355 is placedon the upper non-woven fabric 218 and has water passing holes (notshown) for permitting passage of the liquids to be treated in the samemanner as the perforated plate 220 of the first embodiment. Here, thediameter of the upper non-woven fabric 218 is determined to besubstantially equal to the diameter of the inner diameter of the tubularbody 204, while the diameter of the non-woven fabric compressing plate355 is determined to be slightly smaller than the inner diameter of thetubular body 204.

As shown in FIG. 16, the non-woven fabric compressing plate 355 isadapted to press the activated carbon 202 through the non-woven fabric218. The non-woven fabric compressing plate 355 is also adapted tocooperate, prior to charging the activated carbon 202, with the annularrecess 354 of the flange portion 351 at the upper end of the tubularbody 204, so that particularly the non-woven fabric 246b which is onehaving a larger diameter and which is positioned on the lower layer sideof the non-woven fabrics 246a and 246b can be accurately positioned atthe bottom of the tubular body 204 relative to the filter groove 242.Such an operation will now be explained with reference to FIGS. 17(a) to17(c).

FIGS. 17(a) to 17(c) are explanatory views showing in sequence theoperation for placing the lower non-woven fabrics 246a and 246b on thebottom of the tubular body 204 prior to charging the activated carbon202 into the tubular body 204. As shown in FIGS. 17(a) to 17(c), thefiltration device is prepared in the state where the lid 358 is removedand the O-ring 353 is removed.

Prior to inserting the non-woven fabric 246b into the tubular body 204,the non-woven fabric 246b is positioned in the state where itsperipheral portion is fitted into the annular recess 354 of the flange351 at the upper end of the tubular body 204 as shown in FIG. 17(a).Since the outer diameter of the annular recess 354 is determined to besubstantially equal to the diameter of the non-woven fabric 246b asdescribed above, the non-woven fabric 246b is held in position with itscenter being in coincident with the center of the tubular wall 204. Inthis state, the non-woven fabric 246b has not yet been compressed andhas a relatively greater thickness.

Next, the non-woven fabric compressing plate 355 is placed on thenon-woven fabric 246b. Since the diameter of the non-woven fabriccompressing plate 355 is determined to be smaller than the innerdiameter of the tubular body 204, as indicated by phantom line in FIG.17 (a), the central portion of the non-woven fabric 246b naturally fallsdown into the tubular body 204, while the peripheral portion of thenon-woven fabric 246b which does not contact the non-woven fabriccompressing plate 355 is bent upwardly.

When the non-woven fabric compressing plate 355 is pressed downwardly inthis state, the non-woven fabric 246b goes downwardly with itsperipheral portion bent upwardly along the inner wall of the tubularbody 204 through the gap produced between the non-woven fabriccompressing plate 355 and the inner wall of the tubular body 204 asshown in FIG. 17(b).

The downward movement of the non-woven fabric compressing plate 355 isstopped when the non-woven fabric 246b abuts on the protrusion part 240of the plate support 234 as shown in FIG. 17(c). Thus, the non-wovenfabric 246b is positioned at the bottom of the tubular body 204 with itscenter being in accurately coincident with the center of the tubularbody 204, so that it can be accurately positioned relative to the filtergroove 242.

After the non-woven fabric 246b has been placed on the bottom of thetubular body 204 as described above, the non-woven fabric compressingplate 355 is removed from the tubular body 204, and the non-woven fabric246a on the upper layer side is then inserted into the tubular body 204.Since the diameter of the non-woven fabric 246a is determined to besubstantially equal to the inner diameter of the tubular body 204, thenon-woven fabric 246a may fall to reach the bottom of the tubular body204 by its gravity without aid of the non-woven fabric compressing plate355 and may be placed on the non-woven fabric 246a with its center beingnaturally in coincident with the center of the tubular body 204.

When the activated carbon 202 is charged into the tubular body 204 inthe state where the non-woven fabrics 246b and 246a are placed on thebottom as described above, the peripheral portions of the non-wovenfabrics 246b and 246a are pressed into the filter groove 242 by thegravity of the activated carbon 202.

After the activated carbon has been thus charged, the upper non-wovenfabric 218 is placed on the layer F of the activated carbon 202, and thenon-woven fabric compressing plate 355 is then placed on the uppernon-woven fabric 218. Thereafter, the O-ring 353 is fitted into theannular recess 354, and the lid 356 is mounted, so that the state shownin FIG. 16 can be realized.

As described above, with this embodiment, the annular recess 353 forfitting the O-ring 353 therein is utilized to position the non-wovenfabric 246b, and the non-woven fabric 246b is placed on the bottom ofthe tubular body 204 with its center being in accurately coincident withthe center of the tubular body 204, so that this embodiment isadvantageous in that the fitting operation of the non-woven fabric 246bcan be easily performed and that the subsequent operation for pressingthe non-woven fabric 246b into the filter groove 242 by the gravity ofthe activated carbon 202 can be reliably performed. Thus, theflowing-out of the fine particles of the activated carbon can be furtherreliably prevented.

While the invention has been described with reference to preferredembodiments thereof, it is to be understood that modifications orvariations may be easily made without departing from the spirit of thisinvention which is defined by the appended claims.

I claim:
 1. An oily water separation device comprising a body having aninlet of oily water to be separated, and an oil outlet and a wateroutlet disposed on an upper side and a lower side of said body fordischarging the oils and the water after separation, respectively, ahollow coalescer having therein an oily water passage connected to saidinlet of the oily water to be separated, and a separated oil and waterpassage disposed between said coalescer and a wall part of said body andin communication with said oil outlet and said water outlet, so that theoily water which enters at said inlet into said oily water passage ofsaid coalescer is separated into oil components and water componentsthrough a wall of said coalescer, wherein a back-washing device isprovided for introducing washing liquid into said separated oil andwater passage, and passing the liquid through said coalescer in adirection opposite to the direction for separation of the oily water,and thereafter discharging the washing liquid to the outside of saidbody via said oily water passage, said back-washing device including aback-washing water supply pipe connected to said water outlet of saidbody, and a back-washing water discharge pipe connected to said inlet ofthe oily water, said back-washing water supply pipe being connected toan outlet side of a separate oily water separation tank and saidback-washing water discharging pipe being connected to an inlet side ofsaid oily water separation tank, so that the washing liquid used forback-washing is separated into oil components and water component atsaid oily water separation tank and is circulated for again back-washingsaid coalescer during a back-washing operation, wherein said oily waterseparation tank is upstream from said coalescer for pre-separation ofthe oily water before separation at said coalescer during an oily waterseparation operation.
 2. The oily water separation device as defined inclaim 1, wherein a partition wall is provided in said separated oil andwater passage for producing a rising flow of the oil components and thewater components separated by said coalescer.
 3. The oily waterseparation device as defined in claim 2 wherein said partition wall hasa substantially cylindrical configuration surrounding said coalescer andhas an upper end determined at substantially the same height as an upperend of said coalescer.
 4. The oily water separation device as defined inclaim 1, wherein said oily water separation tank is adapted to receivethe oily water from a washing section disposed on the upstream sidethereof.
 5. The oily water separation device as defined in claim 1,wherein an oily water supply pipe is connected between said outlet sideof said oily water separation tank and said inlet of the oily water ofsaid body, said back-washing water supply pipe has a pipe part extendingfrom said outlet side of said water separation tank and including saidpump, said pipe part also forming a part of said oily water supply pipe,so that said oily water supply pipe branches from said back-washingwater supply pipe, and wherein said back-washing water supply pipe andsaid oily water supply pipe have control valves which are controlled tobe opened and closed, respectively, according to change between the oilywater separation operation and the back-washing operation.
 6. The oilywater separation device as defined in claim 1, wherein said oily waterseparation tank is divided into a plurality of sections for providingalternative overflow and underflow of the oily water or the back-washingwater to be separated.
 7. The oily water separation device as defined inclaim 6, further including a sludge removing device which serves toremove sludges, prior to separation at said oily water separation tank,from the back-washing water which has been used for back-washing saidcoalescer.